2
Here -1 mean exponent 2 is only at 1
and negative sign is without exponent.
Let we have a polynomial
3 2
= x - x + 3x + 5
2
Here look at -x

The exponent is only at x and negative is sign is without exponent. During solution of above polynomial we never convert it toward to positve x^2.

Similarly for further explanation
2
= 5x + 14x + 2
2
Here again focus on 25x .

The exponent is only at x and the co-efficient 7 is without exponent. During solution of above polynomial we never convert 5x^2 to 25x^2 and we can convert 25x^2 if (5x)^2 is given.

We should also understand that the order of operation (BODMAS) is the key of mathematics. and negative sign is take as multiplication so the exponent should be solve before the multiplication